Gliederung

In present, prolongation of ventricular repolarization is the only known specific ECG criterion for Long QT syndrome (LQTS). Several ECG patterns which could help to identify different gene-specific variants of LQTS inside population of affected people have been described as well. So far their diagnostic value is still under discussion. Research for elaborating additional noninvasive diagnostic criteria is relevant. The study aims at evaluation of features of ventricular depolarization (VD) and repolarization (VR) in patients with LQT1 and LQT2 by analyzing the body surface mapping potential distributions of QRS and ST-T.

Patients and methods: The body surface potential mapping (BSPM) was carried out in 27 children (mean age 12.1Â±2.8) with congenital LQTS (16 girls and 11 boys). The family history, course of disease, results of clinical tests and genetic analysis (13 pts) were used for determining of LQTS types. The LQT1 was found in 10 genetically tested pts; and LQT2 was found in another 3 pts. Computer electrocardiographic system “Cardiag” (The Czech Republic) with simultaneous ECG registration in 80 unipolar chest leads was used. Isopotential and isointegral maps of QRS and ST-T were computed. Control group consisted of 20 children, aged from 5 to 17(14.7Â±2.9), without cardiac arrhythmia (7 girls and 13 boys).

Results: 70% (7) of genetically tested LQT1 pts revealed additional negative extremes during VD in the middle of ventricular septum and anterior wall of LV projections. The potential distributions during VR revealed additional positive extremes in approximately the same location in 60% of these children. Combined abnormalities were found in 50% of all LQT1 cases. In all three genetically confirmed LQT2 pts wide zone of negative potentials on anterior chest surface during VD and extensive zone of negative potentials during VR on the right and middle chest surface were found. The same specific peculiarities of VD or VR were found in 13 of 14 non-genetically tested children with congenital LQTS and only in 4 of 20 children in a control group (20%).

Conclusion: BSPM reveals specific abnormalities of depolarization and repolarization in children with congenital LQTS. This could be useful for identification LQT1 and LQT2 pts before performing molecular genetic studies.